Innovative Solutions - Case Studies

Energy-Recovery Units Reduce Costs, Avoid Air-Quality Problems

On the campus of Rockingham Junior High School in Rockingham, N.C., where hot and humid weather is common during spring, summer, and fall, buildings are heated and air-conditioned with unit ventilators and fan-coil units connected to a two-pipe hot-water or chilled-water system. During cooling season, chilled water is produced by an air-cooled chiller; during heating season, hot water is produced by a gas-fired boiler. All ventilation is provided through the unit ventilators, which are connected to the outdoors.

For a three-story classroom addition, Richmond County Schools wanted an HVAC system that complemented and supported the existing HVAC equipment and avoided the severe mold and mildew problems newly constructed schools in the area were experiencing because their mechanical ventilation systems did not treat outdoor air independently.

The district installed two Greenheck ERCH energy-recovery units—one 7,500 cfm, the other 7,900 cfm.

With the ERCH units, chiller capacity was reduced by 36 tons, while boiler capacity was reduced by 129 Mbh. Additionally, a unit ventilator serving a typical classroom was downsized to 1,000 cfm of supply air; a classroom unit ventilator conditioning outdoor air directly would have had to been sized at 1,500 cfm. What's more, the cooling-load requirement of a typical classroom was reduced by more than 1.5 tons. Additional cost savings were achieved through the installation of a smaller hydronic piping system, which was made possible by the energy recovery units' reduction of system gallons per minute by an estimated 25 percent.

After one year of operation, the school's principal said he was very pleased with the indoor-air quality provided by the HVAC system.Greenheck Fan Corp. P.O. Box 410 Schofield, WI 54476-0410 715-359-6171www.greenheck.com

Duct Liner Provides Insulation, IAQ Protection, Noise Attenuation

The architects and engineers for the new Rosa Parks Elementary School in Mankato, Minn., hoped to achieve a return on the school district's $21 million investment by minimizing operating costs and designing a school that is long-lasting. Part of that strategy included the selection of AP Coilflex Acoustic Duct Liner, a fiber-free alternative to other duct liners.

Mike Dolejs, owner of Dolejs Associates Inc., the mechanical engineering firm, liked the fact he could insulate duct from the inside, which is better for sound attenuation. With a noise-reduction coefficient of 0.60 and a sound-transmission value of Class 25 when applied to sheet metal, AP Coilflex exceeds ASTM C1071, Standard Specification for Fibrous Glass Duct Lining Insulation (Thermal and Sound Absorbing Material), in terms of sound performance.

Coilflex's smooth, cleanable surface maintains its integrity despite the air velocities within a duct. Additionally, it is made with Environmental Protection Agency-registered Microban antimicrobial treatment, which provides a higher level of protection against mold.

Dolejs expects the Coilflex duct liner to last a long time. This is a great benefit to schools that often wait many years for bond approval to pave the way for much-needed repairs. Unfortunately, not all school districts take the life-cycle cost of insulation into account.

"What school districts have to realize is that HVAC insulation represents only about one-half of 1 percent of the total construction cost of a new school," Kartik Patel, global HVAC market manager for Armacell, said. "These costs pale in comparison to a costly mold remediation."Armacell LLC 7600 Oakwood Street Ext. Mebane, NC 27302 919-304-3846www.armacell.us

Soon after Park Potomac Place, a luxury high-rise condominium in Potomac, Md., opened, residents started to complain about noise from the kitchen hoods and ducts. During troubleshooting, the traditional constant-speed exhaust systems were found to be exhausting large volumes of conditioned air to the outdoors.

The technical team found that the installation of an EXHAUSTO MBES demand-controlled exhaust system could be a viable solution and would be easy to retrofit. Initial savings calculations indicated substantial savings could be achieved. A test system consisting of an EXHAUSTO BESB insulated box ventilator, along with a PID-based controller that monitored and maintained proper pressure and airflow at all times, depending on the demand for kitchen-hood use, was installed. The test system confirmed that the exhaust rate could be reduced dramatically and that energy savings were possible.

The installation of the EXHAUSTO MBES systems added comfort for the owners and resolved all of the noise problems that were experienced. The kitchen exhaust systems operate at full speed for less than 60 min a day—the original system was operating at full speed 24 hr a day. The energy savings from using variable-speed fans amounted to almost $10,000 per year, but even bigger savings were generated through the reduction of exhausted conditioned air. The EXHAUSTO MBES demand-controlled exhaust system saves almost $75,000 on heating and air conditioning annually. That has resulted in a payback of less than 14 months and a five-year return on investment of more than 500 percent.EXHAUSTO Inc. 1200 Northmeadow Pkwy., Suite 180 Roswell, GA 30076 770-587-3238http://us.exhausto.com

Pump Connector Helps Achieve 25-Percent Increase in Suction Pressure

The Indiana University Cyclotron Facility (IUCF) in Bloomington, Ind., is a state-of-the-art multidisciplinary facility. At peak operation, it requires 4.0 megawatts of power. With this power load, cooling of equipment is critical.

When the facility was built, two 200-hp, 3,700-gpm vertical split-case double-suction chilled-water pumps were installed in an area with inadequate overhead clearance, Bill Starks, IUCF mechanical designer, said.

"When we first started up the pumps," Starks said, "we were going through bearings and wearing out the impellers in three months' time. The pump manufacturers confirmed it was a piping issue. It's very critical, especially on a split-case double-suction pump. It has to be equal flow to each side. Otherwise, if the flow is concentrated to one side, it will result in an uneven thrust load on the impeller. The uneven load would wear out the bearings and also cause the impeller to shift to the side. Eventually, the impeller will start hitting the housing."

A CRV Flex pump connector from The Metraflex Co. increased suction pressure by about 25 percent, from 3.5 to 4.5 lb, and increased output pressure by 10 psi at the same flow rate.

"We've been running six months on our backup pump without bearing failure or any increase in noise," Starks said. "Usually, the bearings would start to get noisier, or you start wearing the impeller, and you get some type of cavitation noise. Right now, it's still the same as Day 1."

The IUCF is so pleased with the performance, it is planning to replace the diffuser on the main pump with the CRV Flex.The Metraflex Co. 2323 W. Hubbard Chicago, IL 60612 312-738-3800www.metraflex.com

An environmental-health and safety engineer for one of the world's largest manufacturers of specialty metals and chemicals, Jason Desler was looking for safety-shower and emergency-eyewash solutions for 13 metal-manufacturing facilities spread over 180 acres of desert, where ambient-temperature conditions range from sub-zero to well above tepid-water standards.

Working with Keltech engineers, Desler carefully evaluated the project requirements and challenges. Shower- and eyewash-fixture specifications were paired with a variety of Keltech CLE emergency-eyewash and SN safety-shower heaters. Standard options were added as needed to meet location and environmental particulars.

Keltech provided more than 116 safety-shower and emergency-eyewash heaters, fixtures, and integrated systems. Employees have access to a safety-shower system or emergency-eyewash station every 45 to 55 ft throughout the 13 facilities and surrounding environment.

Keltech's solution complied with Occupational Safety & Health Administration standards and exceeded American National Standards Institute requirements and other industry and company standards. The heaters rapidly heat water safely and provide an unlimited and continuous supply of tepid (80ºF) water.

Some heaters were engineered with freeze-protection packages that allow them to perform in temperatures as low as -23°F. So that the heaters maintain the proper tepid-water range regardless of the ambient temperature, patented internal controls monitor conditions within the units and purge water exceeding tepid-water standards from the supply system.

The heaters are equipped with NEMA 4 enclosures, which keep airborne contaminants from internal components and protect units from corrosion and premature failure.

The heaters are projected to save Desler’s employer more than $349,000 a year in energy costs alone.Keltech Inc. 729 S. Grove St. Delton, MI 49046 1-800-999-4320www.keltech-inc.com

Rooftop Units Reducing School’s Operating Costs, Environmental Impact

At Eagle Mountain Elementary School in Fort Worth, Texas, older HVAC units were noisy and not very energy-efficient.

Single-zone VAV systems provide significant energy savings and are quieter and provide better humidity control than traditional constant-volume units. The Eagle Mountain Elementary School units include air-side economizers so cool outside air can be used when practical. This provides even greater energy savings. All of the units include a factory-installed 115-V convenience outlet for easy maintenance.

When teachers and students returned to school after summer vacation, they noticed a quieter and more comfortable classroom environment. The variable-speed fan provides a reduction in classroom noise, while the single-zone VAV units precisely control the temperature of the classrooms. Eagle Mountain-Saginaw Independent School District was able to significantly reduce the school's total energy usage. The geothermal heat pump provides significant energy savings year-round, while the single-zone VAV system provides significant energy at part-load conditions. The operation of the geothermal heat pump in the single-zone VAV configuration with an air-side economizer allows Eagle Mountain-Saginaw to significantly reduce the school's environmental impact and operational costs.AAON 2425 S. Yukon Ave. Tulsa, OK 74107 918-583-2266www.aaon.com

Air/Dirt Separator Keeping University's Chilled-Water Loop Clean

As facilities manager for the three-building Veterinary Medicine Complex at Kansas State University in Manhattan, Kansas, Dennis Ahlvers is charged in part with keeping occupants comfortable. Air in the chilled-water loop long had made his job more difficult, but when one of six chillers supplying chilled water to the complex was replaced, he was faced with another problem.

"The air in the system would cause pumps to lose their prime, and after the addition of the new piping for the chiller, there was dirt in the system, too," Ahlvers said.

Ahlvers had an 8-in. Spirovent high-velocity combination air/dirt separator from Spirotherm Inc. installed ahead of the pump that supplies return chilled water from the complex to the new chiller.

Spirovent employs the patented Spirotube coalescing/barrier medium, which allows air and dirt to break free of the flow path in hot- and chilled-water systems. Spirovent's unique design makes achieving peak efficiency in a relatively small vessel possible.

"We have had no air and dirt problems after installing the Spirovent in the system, even though we had the chilled-water system opened up completely," Ahlvers said. "It cleaned up the system in a short period of time with no air problems."

The university intends to install a Spirovent unit on each of its chillers.

Available in sizes to 36 in. and able to handle up to 30,500 gpm, Spirovent high-velocity combination air/dirt separators offer the total solution for eliminating air and separating dirt in all types of applications.Spirotherm Inc. 25 N. Brandon Drive Glendale Heights, IL 60139 630-307-2662http://spirotherm.com

For commercial-property owners forever on the lookout for ways to reduce their utility bills, a major opportunity arises when it is time to replace old compressors in HVAC systems. When Harrison Property Group, the owner of 10 hotels, needed to replace an aging 60-ton reciprocating compressor in its chiller at the Holiday Inn in Ocean City, Md., it turned to BITZER.

The chiller consisted of five 60-ton recips using R-22 refrigerant. While BITZER screws often are used to replace OEM screws, this retrofit conversion required additional changes to the compressor mounts, piping, and wiring layouts. After the R-22 was recovered and the recips were removed, the system was flushed of residual oil. The frame was modified to accommodate a screw, with BITZER model CSH7551-50Y-2PU installed. Also installed were a new capacity controller, an electronic expansion valve, and liquid- and suction-line dryers. The system then was evacuated and charged with R-134a.

Robert Walter, Harrison Property Group’s lead mechanic, found an overall energy reduction of 50 percent, for about $600 a month in savings. BITZER screws offer step-capacity modulation (100/75/50/25 percent) or infinite modulation between 100 and 25 percent. This enables the compressor to precisely match the system load and contributes to the energy efficiency of the HVAC system. A bonus is overall sound reduction.

Upgrading to high-efficiency screw compressors in aging HVAC systems is an effective way to reduce overall power consumption while shortening the investment payback period.BITZER US Inc. 4031 Chamblee Road Oakwood, GA 30566 770-503-9226www.bitzerus.com